1. Field of the Invention
The present invention pertains to surgical stapling instruments and, more particularly, to surgical stapling instruments for applying a plurality of staples to body tissue in a substantially simultaneous manner.
2. Description of the Background Art
Suturing tissue and organs is a painstaking and time-consuming part of most surgical procedures. A high degree of skill is needed and the time and care required increases both the cost of surgery, the potential for excessive blood loss and the risk to the patient accompanying prolonged anesthetization. The advent of surgical staplers has facilitated the suturing process in many procedures, allowing uniform and consistent tissue-fastening to be accomplished with the squeeze of a handle or the advancement of a pusher bar after positioning the stapling instrument.
In some procedures, such as anastomosis (i.e., the joining of adjacent hollow organs), closely spaced parallel rows of sutures are required to seal fluid flow on either side of an incision. The capability of modern mass stapling instruments to apply several closely spaced parallel rows of staples has profoundly facilitated these and other procedures.
Mass staplers have evolved into two common forms. In one form, an instrument body has a U-shaped distal portion with a proximal movable jaw generally perpendicular to the instrument body and a distal anvil jaw fixedly or pivotably mounted to a lower portion of the movable jaw. Spaced parallel rows of distally directed staples are inserted into the movable jaw, tissue to be fastened is positioned between the jaws and the jaws are compressed against the tissue to a preset separation gap. A distal force is applied from the handle to drive movable pushers or hammers in the movable jaw distally forcing the staples out of the cartridge, through the tissue and into the anvil jaw where the staple legs are crimped to fasten the tissue. Strekopitor, et al. U.S. Pat. No. 3,080,564, is exemplary of such staplers. Later developments resulted in the adaptation of the instrument to use preloaded replaceable cartridges to carry the staples instead of tediously reloading the movable jaw between uses. Akopov U.S. Pat. No. 3,589,589 exemplifies such instruments. Fully disposable versions of this basic stapler form have been produced as well, primarily to avoid the work and cost associated with proper disassembly, sterilization and reassembly required for reuse.
The second common form of stapling instrument typically has a pair of elongate blunt-nosed jaws extending distally from the handle, one jaw holding a cartridge in which two or more rows of staples are held with the tissue penetrating staple legs aligned perpendicular to the opposite jaw face and the opposed jaw supporting rows of anvils with curved indentations aligned with the staple legs in the cartridge. These indentations bend and clinch the staple legs as the staples are driven into them. Green U.S. Pat. No. 3,490,675 is exemplary of such stapling instruments. In use, the jaws of these instruments are positioned on either side of the tissue to be joined and then closed to a preset separation gap with the tissue held therebetween. A pusher bar, slidably mounted along the instrument body between the handle and the staple cartridge, is advanced distally into the staple carrying cartridge to individually cam driver bars, or hammers, which sequentially force the staples from the cartridge, into and through the tissue to be joined and into the anvils. Usually such instruments also incorporate a knife blade that is driven in tandem with the clinching of the staple legs to produce a clear cut in the tissue between linear rows of staples.
Other instruments apply two-piece surgical fasteners. These fasteners are typically made from biologically absorbable or non-absorbable polymeric materials which cannot maintain a bent or crimped configuration after being deformed. Hence, in addition to a tissue penetrating member having one or more prongs which are driven through one side of the tissue to be joined, such fasteners also require a retaining member which is positioned on the other side of the tissue to receive the prongs of the tissue penetrating member in an interlocking fashion. One such fastener structure and apparatus for applying it are disclosed in Green U.S. Pat. No. 5,156,614.
Unlike staples, two-piece polymeric fasteners require the fabrication of a plurality of differently designed components. Also, when utilizing two-piece fasteners, alignment between the tissue penetrating member and receiving member is critical. A concern with bioabsorbable two-piece fasteners, in particular, is whether they will have sufficient strength to hold the tissue together for a sufficient period of time to allow the tissue to heal prior to being absorbed.
Recently, the adaptation of a stapling instrument to laparoscopic and endoscopic procedures has appeared, as exemplified by Arein, et al. U.S. Pat. No. 5,050,715. This apparatus includes an elongate tube-like body connecting a handle, positioned external to the surgical site, and two opposed jaws, aligned generally coaxially with the body and positionable at the surgical site. A cartridge of staples is carried in one of the jaws and the opposed jaw functions as an anvil. Tissue is clamped between the jaws, then staple driving bars are driven through the cartridge by a series of cam bars to sequentially force the staples through the tissue and into the anvil for clinching.
While prior art mass stapling devices are widely used, they suffer from many disadvantages when used in procedures requiring a secure constriction or ligation of bodily tissue. One of the disadvantages of prior art stapling instruments is that they suture the tissue to be joined from a single side only. Consequently, if some or all of the staples fail to pierce and/or crimp properly during the stapling procedure, layers of tissue may remain unconnected or at best weakly connected to the remaining tissue and prone to separating under tension. Even in fully formed complete staple installations the distribution of compression across and through the tissue is non-uniform as a result of this asymmetry. Another disadvantage of prior art staplers is that the stapler cannot apply rows of staples close to curved organs to minimize the amount of tissue suspended therefrom.